This invention relates to alarm devices such as are used in the fire protection industry. More particularly, it relates to alarm horns of the electronic type which are used to provide audio warnings and are frequently combined with strobe lights to provide an added visual warning such as might be needed to alert the hearing impaired.
There has developed a need to improve alarm horns and particularly to improve their efficiency. In that connection it is an object of this invention to provide a horn which has a more predictable sound output and a tone richer in harmonics and with substantial low frequency components in the 1 KHz region of the audio spectrum, where human hearing is the most sensitive. The low frequency components provide the additional benefit of being more effective in penetrating the walls of a building to provide the necessary alert for occupants located outside of the area where the alarm is placed.
In addition to the above objectives for performance, it is also an objective of the invention to provide a circuit design for electronic horns which will be useful in both 12 volt and 24 volt systems, which will be less likely to experience unpredictable line currents and which will make possible the easy changing of the sound level as well as the nature of the sound.